The craft of coding and pride in their work. Over the last 12 years I have worked with more people than not that hand off code that solves the problem, but is sloppy and not very readable. I've wondered if this is a byproduct of rushing to meet sprint deadlines.

Learning to do proper debugging. Again, 3 orgs in 12 years, and it seems like the debugging skills of those coming into the industry are getting worse. Personal observation, so take it for what it is, but it seems like even developers 2 or 3 years into the industry still don't know how to use debugging tools or have a "system" for troubleshooting and investigating an issue.